Recent advances in semiconductor performance have been driven in no small part by increased manufacturing precision and reduced device geometries. As feature size shrinks, the associated circuits become more sensitive to contamination during the manufacturing process. The cluster tool has been an important development in semiconductor manufacturing. By providing multiple tools within a single chassis, several manufacturing procedures can be performed on a semiconductor substrate without exposing it to the outside environment. The seals within the cluster tool can be used to create different atmospheric zones. For example, the process modules and the central transfer chamber may operate in a vacuum while the load lock and substrate transport carrier operate in an inert gas atmosphere. Furthermore, because the substrate is never directly exposed to the fab environment, a low particle atmosphere can be maintained around the substrate while the rest of the fab operates with less stringent controls.
The sealed design of the cluster tool protects the substrate from outside contaminants, but outside contaminants are not the only threat to the substrate. Many of the manufacturing procedures carried out within the cluster tool may result in residues that are capable of damaging the substrate. For the purposes of this disclosure, residue may refer to a liquid film, a solid contaminant with or without the potential to outgas, particulate matter, any combination thereof, and/or any other undesirable compound in solid, liquid, or gaseous form. Examples of manufacturing procedures that may leave a residue on the substrate include wet etching, dry etching, ashing, stripping, metal plating, CMP, and/or any other suitable procedure. To illustrate, wet etching procedures apply etchants (e.g., HNO3, HF, KOH, and/or TMAH) to the substrate 12. These etchants may remain on the substrate 12 after etching is completed. Dry etching process gases can include an oxygen-containing gas, fluorine-containing gas (e.g., NF3, CF4, SF6, CH2F2, CHF3, and/or C2F6), chlorine-containing gas (e.g., Cl2, CHCl3, CCl4, and/or BCl3), bromine-containing gas (e.g., HBr and/or CHBr3), iodine-containing gas, other suitable gases or plasmas, and/or combinations thereof. Sulfur, fluorine, chlorine, bromine and other reactive atoms may bond to the photoresist during dry etching and later outgas to form destructive compounds including SO2 and HF. Stripping processes can leave residues of cleaning solutions including H2SO4 (sulfuric acid) and H202 (hydrogen peroxide).
Residue damage is not limited to direct harm to the substrate through such processes as hazing, erosion, and corrosion. Residue may trap particulate matter, distort lithographic imaging, and prevent other process chemicals from performing a desired effect. Residues can form directly on substrates through manufacturing procedures, can condense on substrates from the ambient environment, and can be deposited by other mechanisms.
Systems and methods to reduce residue and residue vapor have the potential to dramatically improve yield and are of significant value.